In 10 ABY,[4] Thimram was stationed at the Emperor's Citadel on Byss with another Dark Side Adept, Gwellib Ap-Llewff. A Jedi Knight and member of the Alliance to Restore the Republic, Luke Skywalker, had been captured by the Empire, and was to be brought before Emperor Palpatine, who by this time was inhabiting a clone body. A Universal Energy Cage brought the captive to the Citadel, where he was received by Thimram, Ap-Llewff, and several other Dark Side Adepts. Upon exiting the cage he had been held in, Skywalker attacked several of the Adepts with the Force, claiming that he would enter the Citadel of his own volition. Thimram was amused, and he ordered Ap-Llewff not to hurt Skywalker, but to keep him covered on his short journey to Palpatine's location.[3] Later that year, Palpatine was definitively killed, and Byss was obliterated by the Galaxy Gun superweapon.[5]

Thimram made sure that the Emperor's orders were executed with swiftness and efficiency. As a result, he became one of the most feared and powerful individuals within the Galactic Empire.[1] Thimram was amused by the way in which Skywalker conducted himself while on Byss, and was highly derisive of the Jedi's ability to act in accordance to his own free will.[3]